As known, washing machines of the type comprising at least one washing chamber in which the devices, e.g. the animal containing tanks, to be subjected to treatment are positioned, are normally used for washing equipment used in research laboratories, in particular but not solely for washing the animal containing tanks used in stables.
The devices arranged inside the washing chamber and intended to be subjected to the treatment are generally indicated with the term “load”.
In this washing chamber, there are wash water distribution means, said means typically comprising rods supporting a plurality of nozzles. Said rods generally support a plurality of nozzles for the distribution of wash water and a plurality of nozzles, different from the first ones, for the distribution of rinse water.
Again, according to a consolidated state of the art, the washing machines being referred to may be grouped into two different types, the type mainly depending on the machine dimensions.
Machines of smaller dimensions, and therefore having simpler architecture, advantageously comprise a water accumulation basin arranged close to the bottom of the washing chamber, adapted to collect the water distributed by the water distribution means, be it wash water or rinse water.
During the washing step, the water contained in the accumulation basin is recirculated by a pump towards the water distribution means in the washing chamber. Once distributed onto the load by means of the nozzles provided on the rods, the wash water falls into the accumulation basin provided at the bottom of the chamber.
The wash water is recirculated several times between the basin and the nozzles in order to optimize the amount of water used in this step. Since the load is dirty, the washing is also effective if the water in the accumulation basin becomes increasingly dirty at each recirculation.
When the load is to be rinsed, the rinse circuit of the machine takes the clean water directly from the mains and directs it to the nozzles in the washing chamber dedicated to rinsing, however not before having heated it to a temperature of about 82° C. by means of accumulation in a specific basin normally called “boiler”, in which heating means are present (e.g. a common electric resistor).
The rinse water which is sprayed onto the load by means of the rinse circuit nozzles also falls back into the wash/rinse water accumulation basin, which is provided with an overflow which drains the water directly into the drainage system.
Therefore, the rinse water always contributes to renewing the washing bath because the addition of clean rinse water involves a renewal of the wash water, the washing being performed by recirculating the water which accumulates in the wash water accumulation basin.
Since the rinse water which mixes with the wash water in the accumulation basin alters the concentration of detergents normally provided in said washing bath, there are advantageously provided means for supplying detergent substances capable of restoring the proper concentration of detergents in the washing bath.
The type of machine just described thus provides for the wash water to perform a closed cycle during washing. For this reason, although the addition of clean mains water during the rinsing step partially dilutes the concentration of “dirt” in the bath contained in the washing basin, this water becomes increasingly dirty during the various washes, and for this reason the washing bath is to be replaced after a given number of wash cycles.
The second type of washing machine includes a water collection reservoir at the bottom of the washing chamber.
Therefore, the wash water is not collected in an accumulation basin arranged at the bottom of the washing chamber but there are instead two separate basins, one basin for the wash water and one basin for the rinse water, and the reservoir does not serve as an accumulation basin but only as a collection basin for the water which falls from the load when it is hit by the fluid sprayed by the nozzles.
Similarly to what occurs in the first type of machine described above, also in this case the wash water contained in the washing basin is sent onto the load through distribution means comprising rods and nozzles but, in this case, also due to the presence of a dedicated pump, because the sole pressure of the mains is not generally sufficient.
The wash water is then recirculated by means of a second pump arranged between the reservoir and the washing basin. Once the load has been hit, the wash water falls into the reservoir and from here is recirculated to the washing basin by means of said second pump.
A second basin contains the clean rinse water which originates from the mains. A dedicated pump pressurizes the rinse water which is sent to the rinse circuit nozzles. The rinse water is thus sprayed by means of the nozzles onto the load and falls back into the reservoir. The rinse water is directed from the collection reservoir back to the washing basin, which also in this case is provided with overflow. Therefore, also in this case the supply of clean rinse water in the washing basin contributes to diluting the dirt which accumulates in the washing basin.
The rinse water is heated to about 82° C. in the rinsing basin before being sent to the rinse nozzles.
In order to provide an idea of the dimensions of the washing machine of the second type described herein, it is sufficient to mention that the washing and rinsing basins have volumes of about 200 liters, respectively.
At the end of all wash cycles, the level of the rinsing basin needs to be restored by taking clean water from the mains, and the washing basin needs to be periodically completely emptied.
The washing process with both types of machines described includes adding acid- or alkaline-based detergents to the wash water bath, depending on the type of dirt to be removed, and in a first step it is brought to a temperature normally around 55° C. but which may also be higher, around 75-80° C., in order to thus increase the effectiveness and action of dissolving the substances deposited on the surfaces.
The rinsing step instead occurs at a higher temperature, generally at 82° C. but it may also be around 90° C.
During the washing and rinsing steps, water at a high temperature is therefore sprayed onto the load and thus the washing chamber of the machine fills up with vapors.
Furthermore, as mentioned, since the wash water generally contains detergent chemicals and the rinse water generally contains other chemicals adapted to neutralize the detergent products, the vapors may contain a given amount of chemicals which could be harmful if inhaled.
In order to avoid overpressure phenomena during the entire wash cycle, and especially in order to allow the door of the washing machine to be opened at the end of the cycle while avoiding the operator from being hit by the vapors, the state of the art provides installing, in the upper part of the washing chamber, a centrifuge fan for the extraction of vapors.
As known from the state of the art, the problem of abating the vapors formed in the washing chamber is currently resolved by providing the simple extraction of the vapors which are conveyed to the external environment or to a centralized extraction conduit. In both cases, dispersing the vapors without recovering the heat energy there from in any manner involves significant energy waste, not to mention the fact that the positioning of washing machines inside a laboratory or in the work environment is often generally not such as to allow the machine to be connected in a simple and affordable manner to the ventilation conduits of the building.
Certain solutions of known type include, generally on the larger machines, i.e. according to the second type of machines described herein, recovering heat energy from the vapors by abating the temperature thereof by condensing them by means of a cooling unit onboard the machine.
The operation of a cooling unit is well known, therefore it is not necessary to further describe the operation of this type of machines known from the state of the art, while it is sufficient to describe herein how the vapors generated inside the washing chamber are conveyed to the evaporator of said cooling circuit, the evaporation of the cooling fluid which crosses the cooling circuit in a closed cycle thus causing the condensing of the vapors generated inside the washing chamber.
The cooling cycle provides for the cooling fluid to condense again in a condenser. In the washing machines provided with cooling unit for abatement of vapors, the condenser in which the cooling fluid condenses by yielding heat to the fluid with which the heat exchange occurs is positioned inside the containing basin of the washing bath.
Thereby, the heat yielded from the condensing cooling fluid heats the washing bath thus finally recovering heat energy for heating the washing bath: the heat yielded from the condenser to the bath contributes to maintaining the operating temperature, thus saving energy which would otherwise be supplied by the heating systems (generally electric resistors, vapor/water exchangers and the like) provided on the machine.
However, these known solutions involve certain drawbacks.
Among the main drawbacks are those associated with the positioning of the coil which forms the cooling circuit condenser immerged in the washing bath. It has indeed been mentioned that detergent chemicals are added to the washing bath which are very aggressive and thus corrosive for the material forming the coil.
Another drawback which affects the known systems consists in that if the cooling unit condenser is inside the washing basin, e.g. in the form of coil, it will necessarily require being separated from the other components of the cooling unit, and this involves significant drawbacks during the installation step at the premises of the final user because machines are shipped with the basins disassembled to allow them to pass through smaller building openings: the technician installing the cooling unit is indeed a specialized technician, because the cooling liquid is pressurized inside the cooling circuit. Loading and pressurizing the cooling circuit are delicate operations which require specialized personnel with specific expertise in cooling systems, therefore having the condenser component inside the machine necessarily involves the intervention of a specialized technician also in the steps of installing/maintaining the machine at the premises of the final customer, which results in increasing costs and in any case is inconvenient.
In machines of known type, the positioning of the condenser inside the washing bath is mandatory, because it is not possible to imagine using the rinse water to perform the heat exchange with the cooling fluid. This is mainly due to the fact that, as mentioned, the water in the rinsing basin reaches 80-90° C., and therefore the temperature is too high to allow the cooling of the cooling fluid, and the heat exchange is therefore not possible.
Similarly, the clean water from the mains could be pre-heated with the cooling unit condenser, before the water reaches the rinse water accumulation basin, thus improving the energy efficiency of the machine. However, this is not possible because, as mentioned above, the level of clean water in the rinsing basin is only periodically restored by means of mains water, while the heat exchange in the cooling circuit condenser needs to occur continuously.